EV vs Petrol Cost Calculator UK
Compare the running costs of an electric car and a petrol car, based on your own mileage and charging habits.
By Prakash, Editor
Published 10 March 2026
Updated 15 October 2026
Sources: GOV.UK · Ofgem · Zapmap · Fuel Finder UK
How does the EV vs petrol calculator work?
The calculator estimates the yearly fuel or energy cost of your current petrol or diesel car and of an equivalent electric car, then adds the servicing and road tax figures you enter to give a total for each. The electric side blends your home and public charging rates using the slider, because few drivers charge in only one place.
Petrol and diesel cost uses your MPG converted to litres (1 UK gallon = 4.546 litres) times the fuel price. Electric cost uses your mileage divided by mi/kWh efficiency, times your blended electricity rate.
The defaults are: petrol 174p a litre (UK average, 14 October 2026), home electricity 26p/kWh (the Ofgem price-cap average from 1 October 2026 is 26.32p/kWh), and public charging 75p/kWh (Zapmap's average across all public chargers, September 2026). Your own rates will differ.
Purchase price and depreciation aren't included. This calculator answers "which is cheaper to run", not "which is cheaper overall". Compare the purchase price and resale value of the specific cars you're considering separately.
3 worked examples
All three use petrol at 174p a litre, home electricity at 26p/kWh and public charging at 75p/kWh. Servicing is assumed at £250 (petrol) and £150 (electric), and road tax at £200 for both. These are my assumptions, so replace them with your own.
Example 1 — Mostly home charging, average mileage
8,000 miles/year · petrol 35 MPG · EV 3.5 mi/kWh · 90% home charging
Petrol fuel cost:(8,000 ÷ 35) × 4.546 × £1.74 = £1,808/year
Blended EV rate:(0.9 × 26p) + (0.1 × 75p) = 30.9p/kWh
EV energy cost:(8,000 ÷ 3.5) × £0.309 = £706/year
Result:Petrol total ≈ £2,258 vs EV total ≈ £1,056, a saving of ≈£1,202/year.
Example 2 — 50/50 mixed charging, higher mileage
14,000 miles/year · petrol 42 MPG · EV 3.8 mi/kWh · 50% home charging
Petrol fuel cost:(14,000 ÷ 42) × 4.546 × £1.74 = £2,637/year
Blended EV rate:(0.5 × 26p) + (0.5 × 75p) = 50.5p/kWh
EV energy cost:(14,000 ÷ 3.8) × £0.505 = £1,861/year
Result:Petrol total ≈ £3,087 vs EV total ≈ £2,211, a saving of ≈£876/year. It is smaller than in Example 1 even though the mileage is higher, because of the heavier public charging.
Example 3 — No home charging, all public
A driver without off-street parking who relies entirely on public chargers.
8,000 miles/year · petrol 40 MPG · EV 3.5 mi/kWh · 0% home charging, public at 75p/kWh
Petrol fuel cost:(8,000 ÷ 40) × 4.546 × £1.74 = £1,582/year
EV energy cost (100% public):(8,000 ÷ 3.5) × £0.75 = £1,714/year
Result:Petrol total ≈ £2,032 vs EV total ≈ £2,064. The EV costs ≈£32/year more to run in this case, and it would be more on rapid chargers.
The difference between Example 1 and Example 3 is charging location alone. Your share of home charging is the biggest lever in this calculator. Without home charging, the running-cost case for an EV can disappear.
Home vs public charging costs
Home charging is usually the cheapest way to run an electric car. Some EV-specific tariffs offer much lower overnight rates (around 8–9p/kWh has been reported for tariffs such as Octopus Go, but rates vary by region and change, so check your own quote).
| Charging type | Cost per kWh | Source / note |
|---|---|---|
| Home, standard tariff (price-cap average) | 26.32p | Ofgem, from 1 October 2026 |
| Home, off-peak EV tariff | about 8–9p | Approximate and varies by supplier and region |
| Public AC (slow/fast) | 54p | Zapmap Price Index, September 2026 |
| Public rapid and ultra-rapid | 79p | Zapmap Price Index, September 2026 |
| All public chargers (average) | 75p | Zapmap Price Index, September 2026 |
These are pay-as-you-go averages, and membership schemes and promotions can lower what you pay. Workplace charging depends on your employer.
Electric car road tax
Electric cars no longer have a zero rate. Under GOV.UK's 2026/27 rates, an electric car registered from 1 April 2017 pays a £10 first payment and then the same £200 standard rate as petrol and diesel cars. Zero emission cars registered between March 2001 and March 2017 pay £20 (Band A).
An extra £440 a year for 5 years applies when the list price is over £40,000 (petrol and diesel) or £50,000 (electric). GOV.UK's page says this applies to electric cars registered between 1 April 2025 and 31 March 2026 and doesn't say what applies after that, so check the current rules if you're buying a newer car. The calculator doesn't add the supplement, so enter the full road tax figure in the road tax boxes if it applies.
In London, electric cars now get a 25% discount on the Congestion Charge rather than the previous exemption (the charge rose to £18 a day on 2 January 2026). See our UK Road Tax Explained guide and the Road Tax Calculator for every rate.
Common calculation mistakes
Assuming 100% home charging
Even drivers with home chargers sometimes top up in public. Examples 1 and 2 show how much the home/public mix changes the saving.
Using official efficiency figures
Official MPG and EV range figures come from standardised tests, and real driving, particularly at motorway speeds and in cold weather, is often less efficient. Use figures from your own driving or from owners of the same car.
Ignoring the public charging gap
Public charging costs several times what home charging costs per kWh. For drivers who depend on it, an EV can cost more to run than a petrol car, as Example 3 shows.
Assuming electric cars are exempt from road tax
Older comparisons often show electric cars as exempt. That is no longer the case, so enter the road tax your car actually pays.
Using diesel MPG with the petrol price
If you're comparing against a diesel car, change the fuel price to the diesel price (199p on 14 October 2026).
Ways to maximise EV savings
- Consider an EV-specific home tariff if you can charge overnight, and compare quotes for your postcode.
- Check whether your workplace offers charging, and how it is priced.
- Plan longer trips around cheaper chargers rather than defaulting to the nearest rapid charger.
- Compare public charging networks and membership schemes, as prices vary a lot.
- Compare insurance quotes for the specific EV before you buy.
How we calculate
Petrol/diesel cost = (annual mileage ÷ MPG) × 4.546 × fuel price per litre
Blended EV rate = (% home ÷ 100 × home rate) + ((100 − % home) ÷ 100 × public rate)
EV energy cost = (annual mileage ÷ mi/kWh) × blended rate
Each side's total adds the servicing and road tax figures you enter (defaults: £250 and £200 for petrol, £150 and £200 for electric). The saving or extra cost is the petrol total minus the EV total. Purchase price, depreciation, insurance, tyres and charger installation are deliberately excluded.
Frequently asked questions
Are electric cars cheaper to run in the UK in 2026?
For drivers who charge mostly at home, usually yes. In Example 1 (90% home charging) the EV saves about £1,202 a year on running costs. The saving depends heavily on your home/public charging mix.
What is the best electricity tariff for EV charging?
EV-specific overnight tariffs can offer much lower off-peak rates than a standard tariff, but they vary by supplier and region and often have higher daytime rates. Compare quotes for your postcode and charging pattern.
Do electric cars pay road tax now?
Yes. Under GOV.UK's current rates, electric cars registered from 1 April 2017 pay a £10 first payment and then £200 a year, and a supplement can apply to expensive models. Enter your own figure in the calculator.
How much does public charging cost?
Zapmap's Price Index put the average across all public chargers at 75p/kWh in September 2026, with AC chargers around 54p and rapid chargers around 79p. Home charging on a standard tariff is about 26p/kWh.
Is an EV still cheaper if I can't charge at home?
Not necessarily. If you rely on public chargers at around 75p/kWh, the running cost can match or exceed a petrol car's, as Example 3 shows. There can be other reasons to choose an EV, but the running-cost case is weaker without home charging.
References & data sources
- GOV.UK — Vehicle tax rate tables. Standard rate, first payment and expensive car supplement for electric and other cars.
- Ofgem — Energy price cap, 1 October to 31 December 2026. Average electricity unit rate of 26.32p/kWh.
- Zapmap — UK EV Charging Price Index. Average public charging prices (75p/kWh overall, 54p AC, 79p rapid), September 2026.
- Fuel Finder UK — UK Fuel Price Index. Average petrol (174.1p) and diesel (199.1p) prices on 14 October 2026.
- Transport for London — Congestion Charge. Current charge and discounts.
Prices were checked on 15 October 2026 and change often. Check current tariffs, charger prices and fuel prices before making a purchase decision.
Prakash
Prakash is the founder and editor of UK Driving Tools. He maintains the site's calculators and guides and checks the rates and rules they use against official UK sources, such as GOV.UK, the DVLA, HMRC and Transport for London, before publishing.
Pages are drafted with the help of AI tools and then checked by the editor. He isn't a lawyer, accountant or UK-qualified adviser, so every page lists its sources and states what its calculator can't tell you. Nothing on this site is legal or financial advice.
Pages on UK Driving Tools are drafted with the help of AI tools. Before publishing, the figures and rules on each page are checked against the official source named on the page, and calculator examples are tested against the working formula. Pages are updated when rates or rules change. Our Editorial Policy explains the full process, including how to report a mistake.
Spotted a mistake or an out-of-date rate? Let us know and we'll check it against the official source.